1. Field of the Invention
The present invention relates generally to the cleaning and hygienic maintenance of oral appliances. More particularly, the present invention relates to the cleaning of removable orthodontic appliances, such as removable tooth repositioning appliances.
A variety of removable orthodontic and other oral appliances have been developed over the years for different purposes. Of particular interest to the present invention, a number of these appliances are formed from clear, translucent, or tooth-colored materials in order to make the appliances xe2x80x9cinvisiblexe2x80x9d or at least reduce their visibility during use. Since these appliances are used in the oral environment, however, they are subject to discoloration and contamination from a number of sources. For that reason, as well as for simple oral hygiene, it is necessary to periodically clean and preferably sanitize the appliances prior to replacement by the patient.
A number of cleaning systems have been developed for removable oral appliances over the years. Most common are cleaning systems for removable dentures. Most simply, in the past, patients have cleaned dentures using brushes and toothpaste, as well as other stronger cleaning materials. More advanced cleaning systems for dentures rely on ultrasonic action to enhance the cleaning ability of the cleaning system which is used.
Recently, orthodontic systems comprising multiple xe2x80x9calignersxe2x80x9d have been developed and are marketed by Align Technology, Inc., under the tradename Invisalign(copyright) System. The aligners are thin-shell polymeric appliances which are shaped to progressively move teeth from an initial configuration to a final desired configuration. The aligners are molded plastic devices formed from polycarbonate and more recently from polyurethane materials. The aligners are intended to be clear and are worn for periods from one to several weeks in each stage of treatment before being replaced by a new aligner.
During the use of any single aligner, it is desirable to clean the aligners once a day. The cleaning, however, must be of a relatively short duration since the aligners are intended to be worn at all times, other than when eating, during tooth-brushing, or when the aligner is cleaned. Thus, the possibility of soaking the aligners overnight or for other extended periods is not possible for the aligners of the Invisalign(copyright) System.
For these reasons, it would be desirable to provide improved apparatus and methods for cleaning removable oral appliances, such as aligners of the Invisalign(copyright) System. It would be further desirable if such apparatus and methods were useful for other removable oral appliances, such as plastic retainers, tooth positioners, and the like. Such apparatus and methods should be able to clean the removable appliances in a very short time, preferably in less than 30 minutes, while providing a high degree of cleaning so that the clear or translucent nature of the appliance is not significantly diminished. The apparatus and methods should of course not leave any residual materials or effect on the appliances which would diminish their intended use or present risk to the patient in any way. Such apparatus and methods should further be convenient to the patient, preferably requiring little effort other than initiating a cleaning cycle, and should be robust and reliable so that the apparatus does not fail, even after repeated uses. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
The Invisalign(copyright) System is generally described in U.S. Pat. No. 5,975,893, the full disclosure of which is incorporated herein by reference. Aligners in the Invisalign(copyright) System are presently available in both polycarbonate and polyurethane materials. Cleaning of the Invisalign(copyright) System aligners has heretofore been preformed by patients on an ad hoc basis, typically using brushes, denture cleaners, and other non-optimized approaches.
Denture cleaning tablets and compositions are described in U.S. Pat. Nos. 3,936,385; 3,821,117; and 4,857,224. Mechanical denture cleaners are described in U.S. Pat. Nos. 729,536; 2,744,635; 3,085,583; 3,376,878; 4,986,290; 4,721,124; 4,922,939; 5,421,353; 5,494,531; 5,690,211; 5,758,675; 5,950,644; and 6,213,777B1.
According to the present invention an oral appliance cleaning system comprises a base and a tray in the base for holding the appliance in a bath of cleaning solution. A low frequency driver is also provided in the base for reciprocating the tray about an axis to wash the cleaning solution over the appliance. Usually, the axis will be horizontal so that the tray is rocked with its ends reciprocating vertically and alternating upward and downward strokes. Alternatively, the axis could be vertical, with the tray rotated in a reversing, rotational pattern about the vertical axis.
In a preferred embodiment, the low frequency driver comprises a cradle mounted to pivot about a horizontal axis within a cavity in the base. The cradle will have a receptacle for removably receiving the tray which holds the appliance. Thus, the appliance-holding tray can be removed from the apparatus to facilitate washing, placement of the appliance into the tray, filling the tray with cleaning solution, etc. Usually, the tray will have a removable cover so that the tray can be closed prior to placement into the cradle within the base. This is an advantage since it reduces the chance that the cleaning solution will splash from the tray during the cleaning process.
In a specific embodiment, the low-frequency driver further comprises a vertical link attached to one end of the cradle and a reciprocating motor, such as a solenoid or other magnetic driver, attached to the other end of the vertical link. Operation of the motor will reciprocate the vertical link which will in turn rock the cradle. Preferably, the motor will reciprocate at a low frequency in the range from 1 Hz to 10 Hz, preferably in the range from 2 Hz to 5 Hz.
Methods according to the present invention comprise filling a tray with a cleaning solution, placing the appliance in the tray, placing the tray in a cradle, and rocking the cradle at a low frequency, typically in the range from 1 Hz to 10 Hz, preferably in the range from 2 Hz to 5 Hz, to gently but effectively wash the appliance to provide for thorough cleaning and hygiene. Preferably, the tray will be covered prior to initiating rocking of the cradle. More preferably, the cleaning solution comprises a chlorine-based material.
In another aspect of the present invention, an oral appliance cleaning apparatus comprises a base having a cavity, a tray having a removable cover for holding the oral appliance in a cleaning solution, a cradle mounted within the base cavity and having a receptacle for removably receiving the tray, and means in the base for agitating the cradle to clean the oral appliance held within the tray. Preferably, the cradle is mounted in the cavity to pivot about a horizontal axis. More preferably, the agitating means comprises a low-frequency driver for reciprocating the cradle about the horizontal axis at a frequency in the range from 1 Hz to 10 Hz, preferably in the range from 2 Hz to 5 Hz.